In a charged particle beam measurement apparatus typified by a scanning electron microscope, a combination of a scintillator and a photomultiplier tube is used to detect secondary electrons or reflected electrons generated when a sample is irradiated with an electron beam. If light emitted from the scintillator is incident to the photomultiplier tube, photoelectrons are emitted from a photoelectric surface, and the electrons are amplified in the photomultiplier tube. Here, since a pulse interval of a photomultiplier tube output is small in a region where incident light is strong, pulses overlap each other so as to form an analog waveform. However, if light is weakened, respective pulses are discrete, and thus a pulsed output waveform is formed.
As an example of the related art regarding a method of detecting such an analog waveform and a pulsed output waveform, there is a technique disclosed in JP-A-2011-175811 (PTL 1). PTL 1 discloses the following content. A charged particle beam device includes a determination unit that determines whether an output signal is an output signal in a state in which a single charged particle is incident to a detector or is an output signal in a state in which a plurality of charged particles are incident to the detector; and a calculation unit which performs image formation through signal processing based on a pulse count method when determining that the output signal is an output signal in a state in which a single charged particle is incident to the detector and performing the image formation through signal processing based on an analog method when determining that the output signal is an output signal in a state in which the plurality of charged particles are incident to the detector.